Axial piston pulse generator



May 16, 1967 L. KRAMER AXIAL PISTON PULSE GENERATOR 5 Sheets-Sheet 1 Filed April 1, 1965 a all 3 3 F\ o W K M \\v FIG. 2A

INVENTOR. L E0 KRA ME I? AGENT y 16, 1%? L. KRAMER 33mm AXIAL PISTON PULSE GENERATOR Filed April 1, 1965 5 Sheets-Sheet 2 INVENTOR. L 0 Kim NEW BYCQMQ0%Q/ AGENT y 6, mm L. KRAMER 3,319,?23

AXIAL PISTON PULSE GENERATOR Filed April 1, 1.965 5 Sheets-Sheet 5 6 INVENTOR.

L E0 l1 AM MER AGENT 5.1 W May 16, 166 1.. KRAMER AXIAL PISTON FULSE GENERATOR 5 Sheets-Sheet 4 Filed April 1, l965 INVENTOR. LEO KfiA/WE AGENT May 1%, L. KRAMER AXIAL PISTON PULSE GENERATOR Filed April 1, 1965 5 Sheets-Sheet 5 AG ENT United States Patent Ofiice aaram Patented. May 116, 1967 ABSTRACT OF THE DISCLOSURE An impulse tool for driving a fastener including a housing and a spindle relatively movable in the housing, a piston sliding in a piston chamber provided in the housing and engaged with a cam fixed on the spindle and causing the piston to reciprocate in its chamber as the spindle rotates in the housing. The piston chamber contains a hydraulic fluid. A passage is connected to the piston chamber to relieve excess pressure from the piston chamber and is arranged to be blocked by the piston during its pumping stroke whereby the piston begins to compress the fluid in the piston chamber and, as a result, abruptly meets a resisting force causing the housing and spindle to be momentarily locked together to transmit a torque impulse to the fastener. The piston chamber and the fluid passage are arranged so that the housing and spindle are released for further relative rotation very quickly after they are abruptly locked together so that the tool can create a rapid series of torque impulses for application to the fastener.

This invention relates to impulse tools and more particularly to an improved impulse tool of the axial piston type.

Heretofore, impulse tools for applying a torque to an object and/or for use as a source of fluid impulses for operating a tool are disclosed in US. Patent No. 3,116,617 issued Jan. 7, 1964, to D. K. Skoog, and in US. patent application Ser. No. 285,160 filed Mar. 18, 1963, by D. K. Skoog, now Patent No. 3,263,426.

Other conventional power tools are of the type shown in the following US. patents:

461,813, Oct. 27, 1891, J. W. Cahow. 838,149, Dec. 11,1906, J. C. Wands. 859,087, July 2, 1907, L. M. J. C. Levavasseur. 1,347,315, July 20, 1920, R. L. Williamson. 1,357,756, Nov. 2, 1920, R. L. Williamson. 1,422,929, July 18, 1922, R. T. Cooke. 1,537,628, May 12, 1925, J. A. Street. 1,610,405, Dec. 14, 1926, S. G. Wingquist. 1,611,940, Dec. 28, 1926, H. Bohmer. 1,667,274, Apr. 24, 1928, T. Walsh et al. 1,685,839, Oct. 2, 1928, A. D. Dubois. 1,725,833, Aug. 27, 1929, L. G. Simpson. 2,035,514, Mar. 31, 193 6, F. E. Staats. 2,132,631, Oct. 11, 1938, W. S. Jones. 2,253,299, Aug. 19, 1941, F. A. Howard. 2,311,580, Feb. 16, 1943, S. N. Silverstone. 2,395,355, Feb. 19, 1946, G. E. Thompson. 2,434,590, Jan. 13, 1948, O. F. Runde. 2,497,993, Feb. 21, 1950, H. A. James. 2,546,062, Mar. 20, 1951, H. Ernst. 2,546,633, Mar. 27, 1951, A. Y. Dodge. 2,565,579, Aug. 28, 1951, R. H. Thorner. 2,595,274, May 6, 1952, C. A. Latimer. 2,609,674, Sept. 9, 1952, L. C. Groat. 2,621,480, Dec. 16, 1952, G. F. Wales. 2,708,018, May 10, 1955, R. A. Dudley. 2,720,297, Oct. 11, 1955, G. A. Arvidson.

2,741,352, Apr. 10, 1956, D. Stevens et al. 2,745,528, May 15, 1956, L. A. Amtsberg. 2,806,366, Sept. 17, 1957, F. B. Woestemeyer. 2,809,734, Oct. 15, 1957, C. L. Graybill. 2,881,885, Apr. 14, 1959, R. S. Short. 2,883,938, Apr. 28, 1959, M. A. Shaffner. 2,900,811, Aug. 25, 1959, J. E. De Selms. 2,947,180, Aug. 2, 1960, J. Oros.

2,963,134, Dec. 6, 1960, A. Banner. 2,976,973, Mar. 28, 1961, H. Stansfield et al. 2,979,962, Apr. 18, 1961, J. E. Nindel. 2,986,024, May 30, 1961, B. D. Power. 3,104,743, Sept. 24, 1963, H. C. Reynolds.

Conventional impulse tools have leakage between the lands of the housing means, the spindle blade and the shank portion of the spindle means thereby requiring close tolerances in the fabrication of these parts.

It is the general object of the present invention to avoid and overcome the foregoing and other difficulties of and objections to prior art practices by the provision of an axial piston type impulse tool which:

(1) Substantially reduces fluid leakage in the impulse tool;

(2) Provides a frictional assist to develop and to transmit torque;

(3) Reduces the number of close tolerance sealing elements within the impulse tool thereby decreasing the manufacturing cost and increasing the life of the impulse tool;

(4) Provides a more rigid impulse tool;

(5) Provides a smaller quantity of fluid under compression and produces higher ultimate torque.

The aforesaid objects of the present invention, and other objects which will become apparent as the description proceeds, are achieved by providing an axial piston type impulse tool having a driven member and a driving member mounted together for relative rotation therebetween. These members cooperate together to form a piston cavity and a spindle cavity. Both the piston cavity and the spindle cavity contain a hydraulic fluid. Cam means is positioned in the spindle cavity and rotationally keyed to one of said members. Piston means is slidably mounted in the piston cavity to engage the cam and to rotate with the other of said members. Relative rotation between the members causes the piston means to ride up on the cam means and to pump the fluid in the piston cavity. Passage means is provided to communicate the piston cavity with the spindle cavity and is located in the piston cavity where it is blocked by the piston means during a later portion of its pumping stroke. Blockage of the passage means causes the piston means to be abruptly and momentarily opposed, part way through its pumping stroke, by the compressed fluid remaining in the piston cavity. An abrupt resistance of the piston by the compressed fluid remaining in the piston cavity results in the members being momentarily locked together to apply a torque impulse to the driving member.

For a better understanding of the present invention reference should be had to the accompanying drawings, wherein like numerals of reference indicate similar parts throughout the several views and wherein:

FIG. 1 is a side elevational view of the improved impulse tool of the present invention and showing the housing means connected to the drive means and the piston means in the housing means;

FIG. 2 is a vertical sectional view taken along the line Z-Z of FIG. 1 in the direction of the arrows;

FIG. 2A is an isometric view of the cam means shown in FIG. 2;

FIG, 3 is a view similar to FIG. 2 of an alternative embodiment utilizing valve means, and showing the housing means connected to the drive means and the piston means in the housing means;

FIG. 4 is a view similar to FIGS. 2, 3 of an alternative embodiment showing the spindle means connected to the drive means and the piston means in the spindle means;

FIG. 5 is a view similar to FIGS. 2, 3, 4, of an alternative embodiment showing the housing means connected to the drive means and the piston means in the spindle means;

FIG. 6 is a view similar to FIGS. 2, 3, 4, 5 of an alternative embodiment showing the spindle means connected to the drive means and the piston means in the housing means;

FIG. 7 is a view similar to FIGS 2, 3, 4, 5, 6 of an alternative embodiment showing the impulse tool used as a source of fluid impulses with the spindle means connected to the drive means, piston means in the housing means and the housing means connected to a stationary member;

FIG. 8 is a view similar to FIGS. 2, 3, 4, 5, 6, 7 show ing the impulse tool used as a source of fluid impulses with the housing means connected to the drive means, piston means in the spindle means and the spindle means connected to the stationary member.

Although the principles of the present invention are broadly applicable to power tools, the present invention is particularly adapted for use in conjunction with impulse tools and hence it has been so illustrated and will be so described.

With specific reference to the form of the present invention illustrated in the drawings, and referring particularly to FIGS. 1, 2, an axial piston type impulse tool for applying torque to an object, such as the nut N, is indicated generally by the reference numeral 10.

This axial piston type impulse tool 10 has housing means A and spindle means B in the housing means A. Drive means, such as an air motor or electric motor D is connected through an input shaft 12 (FIGS. 1, 2) to one of the housing means A and the spindle means 13 (in this case the housing means A) to cause relative rotation therebetween. The other of the housing means A and the piston means B (ie the spindle means B) has an output or spindle shaft 14 engageable by a socket 16 with the nut N.

One of the housing means A and the spindle means B (i.e. housing means A in FIG, 2) is provided with a piston cavity 18 and a spindle or low pressure cavity 20, both cavities 18 and 20 being adapted to contain a fluid, such as oil F.

Cam means, such as the cam 22 (FIGS. 2, 2A) has shaft hole 23 and is slidably keyed at 24, 25 to the output shaft 14, rotates on thrust bearing 26, and is disposed in spindle cavity 20. Piston means, such as the piston 28, is disposed in the piston cavity 18 and is engageable with thecam face 30 (FIG. 2A) of cam 22.

The housing means A and spindle means B (in FIG. 2, the housing means A) are provided with passage means, such as return passage 32 in the housing means A, shaft passage 34, 36 in output shaft 14. If more than one piston 28 is employed, a pressure equalizing passage 79 is employed.

Operation Briefly the relative rotation between the housing means A and spindle means B causes the piston 28 to ride up the cam face 30 and to close off the return passage 32 and thereby compress the oil F in the piston cavity 18. The compressed oil F applies a force to the piston 28 thereby imposing a relative torquing between the piston 28 and the cam 22 with attendant rotation of the other of the housing means A and the spindle means B (in FIG. 2, the spindle means B) and resultant application of torque to the nut N.

Referring in greater detail now to FIGS. 1, 2, as the housing means A is rotated by the air motor or electric motor D relative to the cam 22, the piston 28 moves axially in its piston cavity 18.

In FIG, 2 the piston 28 is fully extended into the low pressure cavity 20. At this point, any relative motion between the housing means A and the cam 22 causes the piston 28 to move upward (against action of spring 37) into the piston cavity 18. As the piston 28 moves upward (FIG. 2) into its piston cavity 18 it pushes oil F from piston cavity 18 through return passage 32 through shaft passages 34, 36 to low pressure cavity 20. As the piston 28 continues to move into its cavity 18 it blocks return passage 32 with a subsequent pressure increase in piston cavity 18 as the piston 28 continues to move upward.

As pressure is built up in piston cavity 18 an axial force is applied to piston 28 which piston 28 in turn applies a torque couple to cam 22. Since cam 22 is fixed to the output shaft 14 via shaft key 24 and cam keyway 25 the cam 22 and output shaft 14 must rotate as one unit.

As the piston 28 continues to move upward into the piston cavity 18 the pressure continues to rise until the piston land 38 passes over return passage 32 thereby communicating piston cavity 18 to low pressure cavity 20 via piston passage 39, return passage 32 and shaft passages 34, 36 thereby reducing pressure to essentially zero. At this time the piston 28 will be near the end of its upward travel and continued rotation of the housing means A with respect to the cam 22 brings the piston 28 over the maximum rise point 40 (FIG. 2A) of the cam 22 thereby permitting the piston spring 37 to push the piston 28 downwardly (FIG. 2) out of its piston cavity 18 (as rotation continues).

As piston 28 moves downwardly (FIG. 2) out of its cavity 18 oil F must be transferred from low pressure cavity 20 to piston cavity 18.

It will be understood by those skilled in the art that the housing means A will accelerate freely from the time the pressure in piston cavity 18 is reduced to essentially zero until the piston land 38 again blocks return passage 32. As the housing means A accelerates freely it developes kinetic energy which can then be converted to pressure pulses in piston cavity 18 and to torque pulses at output shaft 14.

Alternative embodiments It will be understood by those skilled in the art that alternatively as shown in FIG. 3 a check valve 42 in line 44 (connecting passage 79 and return passage 32 is used to permit return of oil F behind the piston 28 without cavitation after impulse and when the piston 28 is running down (FIG. 3) the cam 22 For the purpose of limiting the maximum pressure in the piston cavity 18 and hence maximum torque delivered to the nut N, a relief valve 46 in line 48 (connecting passage 79 with passage 36 is employed.

In FIG. 4 the spindle means B is connected to input shaft 12 the pistons 28*, piston cavities 18 etc. are in the spindle means B and the cam 22 is carried by the housing means A". Passage 34 in this case is in the spindle means 13*.

As shown in FIG. 5 the housing means A is connected to the driven shaft 12 and carries the cam 22 The pistons 28 piston cavities 18 etc. are in the spindle means B Passage 34 in this case is in the spindle means B From FIG. 6 it will be appreciated that the input shaft 12 is connected to the spindle means B which carries the cam 22 and the housing means A contains the pistons 28, piston cavities 18 etc.

Referring to FIG. 7 and the operation of the impulse tool as a source of fluid impulses for operating a tool, such as the cylinder '50, the housing means A is tied by a plate to a stationary member, such as a table or wall 54, the spindle means B is connected to input shaft 12 and the pistons 28", piston cavities 18 etc. are in the housing means A". Impulses from piston cavities 1'8 are transferred by impulse transfer means (i.e. passage 56 in housing means A line 58, four way valve 60 and the 62 to one side of piston 64 in cylinder 50. Line 66 connects the other side of piston 64 to valve 60 and line 68 extends from the valve 60 to spindle cavity When manually actuated valve handle 70 is moved downwardly (as viewed in FIG. 1) against the action of the spring, the flow on each side of the piston 64 is reversed.

In FIG. 8 the spindle means B is connected at 74 to a stationary casing 76 of the tool 10 and contains the pistons 28 piston cavities 18 etc. The housing means A is connected to input shaft 12 and carries the cam 22 Impulses are transmitted via passage 56*, line 58 to cylinder 50*, the piston 64 of which is connected to a tool, such as a hammer 78. Passage 34 in this case is in the spindle means B It will be recognized by those skilled in the art that the objects of the present invention have been achieved by providing axial piston type impulse tool which:

(1) Substantially reduces fluid leakage in the impulse tool;

(2) Provides a frictional assist to develop and to transmit torque;

(3)Reduces the number of close tolerance sealing elements within the impulse tool thereby decreasing the manufacturing cost and increasing the life of the impulse tool;

(4) Provides a more rigid impulse tool;

(5) Provides a smaller quantity of fluid under compression and produces higher ultimate torques.

While in accordance with the patent statutes preferred and alternative embodiments of the present invention have been illustrated and described in detail, it is to be particularly understood that the invention is not limited thereto or thereby.

I claim:

1. An impulse tool for applying a series of torque im pulses to an object, said tool comprising:

a driven member;

a driving member mounted on said driven member for relative rotation therebetween;

drive means connected to said driven member;

said driving member being engageable with said object;

said members cooperating to form a piston cavity and a spindle cavity;

a fluid contained in said portion cavity and said spindle cavity;

cam means in said spindle cavity and rotatively keyed to one of said members; piston means in said piston cavity engaging said cam means and rotating with the other of said members whereby relative rotation between said members causes said piston means to ride up on said cam means and to pump said fluid in said piston cavity;

passage means communicating said piston cavity with said spindle cavity and located in said piston cavity where it is blocked by said piston means during a portion of its pumping stroke causing said piston means to be abruptly resisted against further movement partway through its pumping stroke, as a result of the compression of the fluid remaining in the piston cavity, resulting in said members being momentarily locked together to apply a torque impulse to said object.

2. The impulse tool recited in claim 1 wherein said driving member is provided with said piston cavity.

3. The impulse tool recited in claim 1 wherein said driving member is provided with said piston cavity.

4. The impulse tool recited in claim 1 wherein cam means is on said driven member.

5. The impulse tool recited in claim 1 wherein said cam means is on said driving member.

6. The impulse tool recited in claim 1 and having check valve means communicating with said piston cavity and said passage means.

7. The impulse tool recited in claim 1 and having relief valve means communicating with said piston cavity and said passage means.

said

References Cited by the Examiner UNITED STATES PATENTS 2,900,811 8/1959 De Selma 64-26 3,1.16,6.17 1/1964 Skoog 64-26 3,210,959 10/1965 Brown 64-26 3,212,295 10/1965 Vaughn 173-93 FRED C. MATTERN, JR. Primary Examiner.

L. P. KESSLER, Assistant Examiner. 

1. AN IMPULSE TOOL FOR APPLYING A SERIES OF TORQUE IMPULSES TO AN OBJECT, SAID TOOL COMPRISING: A DRIVEN MEMBER; A DRIVING MEMBER MOUNTED ON SAID DRIVEN MEMBER FOR RELATIVE ROTATION THEREBETWEEN; DRIVE MEANS CONNECTED TO SAID DRIVEN MEMBER; SAID DRIVING MEMBER BEING ENGAGEABLE WITH SAID OBJECT; SAID MEMBERS COOPERATING TO FORM A PISTON CAVITY AND A SPINDLE CAVITY; A FLUID CONTAINED IN SAID PORTION CAVITY AND SAID SPINDLE CAVITY; CAM MEANS IN SAID SPINDLE CAVITY AND ROTATIVELY KEYED TO ONE OF SAID MEMBERS; PISTON MEANS IN SAID PISTON CAVITY ENGAGING SAID CAM MEANS AND ROTATING WITH THE OTHER OF SAID MEMBERS 